Hip resurfacing consists in the implanting of a femoral head implant on a resurfaced femoral head, and the resurfacing of the acetabulum for the insertion therein of a cup implant. In such cases, the surgeon judges that the femoral neck is strong enough to remain unaltered, and the femoral head implant is used to replace damaged femoral head bone material. In comparison with total hip joint implanting surgery, the hip joint resurfacing surgery removes a relatively small amount of femoral bone while providing high levels of joint stability.
Different output values are of concern in hip replacement surgery. In order to reproduce a natural and/or improved gait and range of motion to a patient, the position and orientation of the implants, the offset of the femur and the limb length must be considered during surgery. The work of the surgeon during hip replacement surgery will have a direct effect on these output values.
Known hip joint resurfacing surgery techniques presently involve specific tools so as to obtain precise position and orientation for the implants. As various types of reamers are used to resurface the femoral head, alignment steps are performed to align the tools with the cuts to be made. It is, for instance, of nonnegligible importance that the femoral neck not be damaged (i.e., notched) by the reamers, to prevent fracture-prone weakness in the femoral head. Moreover, the resurfacing must be as precise as possible, for instance, to reduce the amount of cement required for implanting the ball head implant to the resurfaced ball head.
Hence, the positioning of the femoral component is vital to the success of hip resurfacing. However, due to the limited exposure of the femoral head in minimally invasive surgery, femoral-axis alignment may be difficult to visualize intraoperatively. Accordingly, radiographic instrumentation, such as a C-arm, is often required, and this adds costs and time to the procedure.